1 /*
2 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License").
5 * You may not use this file except in compliance with the License.
6 * A copy of the License is located at
7 *
8 * http://aws.amazon.com/apache2.0
9 *
10 * or in the "license" file accompanying this file. This file is distributed
11 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
12 * express or implied. See the License for the specific language governing
13 * permissions and limitations under the License.
14 */
15
16 #include "api/s2n.h"
17 #include "tls/s2n_tls.h"
18 #include "tls/s2n_tls13.h"
19 #include "crypto/s2n_rsa_pss.h"
20 #include "crypto/s2n_rsa_signing.h"
21
22 bool s2n_use_default_tls13_config_flag = false;
23
s2n_use_default_tls13_config()24 bool s2n_use_default_tls13_config()
25 {
26 return s2n_use_default_tls13_config_flag;
27 }
28
s2n_is_tls13_fully_supported()29 bool s2n_is_tls13_fully_supported() {
30 /* Older versions of Openssl (eg 1.0.2) do not support RSA PSS, which is required for TLS 1.3. */
31 return s2n_is_rsa_pss_signing_supported() && s2n_is_rsa_pss_certs_supported();
32 }
33
s2n_get_highest_fully_supported_tls_version()34 int s2n_get_highest_fully_supported_tls_version() {
35 return s2n_is_tls13_fully_supported() ? S2N_TLS13 : S2N_TLS12;
36 }
37
38 /* Allow TLS1.3 to be negotiated, and use the default TLS1.3 security policy.
39 * This is NOT the default behavior, and this method is deprecated.
40 *
41 * Please consider using the default behavior and configuring
42 * TLS1.2/TLS1.3 via explicit security policy instead.
43 */
s2n_enable_tls13()44 int s2n_enable_tls13()
45 {
46 s2n_highest_protocol_version = S2N_TLS13;
47 s2n_use_default_tls13_config_flag = true;
48 return S2N_SUCCESS;
49 }
50
51 /* Do NOT allow TLS1.3 to be negotiated, regardless of security policy.
52 * This is NOT the default behavior, and this method is deprecated.
53 *
54 * Please consider using the default behavior and configuring
55 * TLS1.2/TLS1.3 via explicit security policy instead.
56 */
s2n_disable_tls13()57 int s2n_disable_tls13()
58 {
59 POSIX_ENSURE(s2n_in_unit_test(), S2N_ERR_NOT_IN_UNIT_TEST);
60 s2n_highest_protocol_version = S2N_TLS12;
61 s2n_use_default_tls13_config_flag = false;
62 return S2N_SUCCESS;
63 }
64
65 /* Reset S2N to the default protocol version behavior.
66 *
67 * This method is intended for use in existing unit tests when the APIs
68 * to enable/disable TLS1.3 have already been called.
69 */
s2n_reset_tls13()70 int s2n_reset_tls13()
71 {
72 POSIX_ENSURE(s2n_in_unit_test(), S2N_ERR_NOT_IN_UNIT_TEST);
73 s2n_highest_protocol_version = S2N_TLS13;
74 s2n_use_default_tls13_config_flag = false;
75 return S2N_SUCCESS;
76 }
77
78 /* Returns whether a uint16 iana value is a valid TLS 1.3 cipher suite */
s2n_is_valid_tls13_cipher(const uint8_t version[2])79 bool s2n_is_valid_tls13_cipher(const uint8_t version[2]) {
80 /* Valid TLS 1.3 Ciphers are
81 * 0x1301, 0x1302, 0x1303, 0x1304, 0x1305.
82 * (https://tools.ietf.org/html/rfc8446#appendix-B.4)
83 */
84 return version[0] == 0x13 && version[1] >= 0x01 && version[1] <= 0x05;
85 }
86
87 /* Use middlebox compatibility mode for TLS1.3 by default.
88 * For now, only disable it when QUIC support is enabled.
89 */
s2n_is_middlebox_compat_enabled(struct s2n_connection * conn)90 bool s2n_is_middlebox_compat_enabled(struct s2n_connection *conn)
91 {
92 return s2n_connection_get_protocol_version(conn) >= S2N_TLS13
93 && !s2n_connection_is_quic_enabled(conn);
94 }
95